1. Technical Field
The present invention relates to a display device.
2. Description of the Related Art
In recent years, demands for display devices for a mobile apparatus such as a cellular telephone and electronic paper have been growing. In the display devices, one pixel includes a plurality of sub-pixels, the sub-pixels output colors different from each other, and display of each sub-pixel is turned on and off so that various colors are displayed by one pixel. In such display devices, display characteristics such as resolution and luminance have been improved year by year. However, as the resolution is increased, an aperture ratio is reduced. Thus, luminance of a backlight needs to be increased to achieve high luminance, so that power consumption of the backlight is disadvantageously increased. To solve this problem, for example, Japanese Patent Application Laid-open Publication No. 2011-154323 (JP-A-2011-154323) discloses a technique of producing a display output with four colors including white (W) in addition to primary colors such as red (R), green (G), and blue (B) in the related art to secure the luminance. In this technique, a sub-pixel of white (W) improves the luminance and reduces a current value of the backlight accordingly, which reduces the power consumption. When the current value of the backlight is not reduced, the luminance is improved by the white pixel, so that visibility under external light outside can be improved by utilizing the improved luminance.
JP-A-2011-154323 discloses an image display panel in which pixels each including sub-pixels of red (R), green (G), blue (B), and white (W) are arranged in a two-dimensional matrix. FIGS. 2, 22, and 23 in JP-A-2011-154323 illustrate arrays of sub-pixels of red (R), green (G), blue (B), and white (W). However, with the array to which the sub-pixel of white (W) is simply added such as the array disclosed in JP-A-2011-154323, the aperture ratio may be reduced as the sub-pixels constituting one pixel are increased, and the aperture ratio tends to be significantly reduced due to the increase in the number of sub-pixels as the resolution is increased.
For the foregoing reasons, there is a need for a display device that includes a display unit for producing a display output using four or more colors, and can further increase the aperture ratio.